By PATRICK LYONS
Capital News Service
LANSING — New research has linked honeybee colony deaths with insecticides used on corn and soybean seeds, but experts said it’s not the only thing wiping out bees that are essential for pollinating other crops.
Purdue University researchers said that so-called neonicotinoid insecticides have been found in dead hives.
Farmers use the chemicals to treat corn and soybean seeds prior to planting.
The insecticides are spread through the release of talc that keeps the seeds from sticking together inside planters. The talc then settles on plants adjacent to the fields, like dandelions.
Bee populations across the country are experiencing high death rates, said Mike Hansen, the state apiarist for the Department of Agriculture and Rural Development.
“These last four or five years, we have lost about 30 percent to 35 percent of the colonies, depending on the year, every year,” Hansen said.
Honeybee pollination is vital for growing a number of Michigan crops like cherries, blueberries and cucumbers, and commercial beekeepers rent colonies of bees to growers for the pollination season.
Estimates place the impact of honeybee pollination in the state at $1 billion a year and $15 to $20 billion nationwide, Hansen said.
Chris DiFonzo, a field crops entomologist at Michigan State University, said that the first step corn and soybean growers can take to reduce insecticide spread is implementing controls on their planters to capture the talc that escapes into the environment.
Insecticide use has become excessive, with chemicals applied in soils without harmful insect populations, she said.
Corn producers don’t have a choice in using insecticide-treated seeds because all corn seeds sold have already been treated, DiFonzo said.
Soybean growers have the option of not coating their seeds with insecticide, and DiFonzo said growers should test the land before deciding that insecticides are necessary.
“There are always unintended consequences of using pesticides,” DiFonzo said. “If you don’t need to use them, then don’t use them, and don’t put them out into the environment.”
DiFonzo said that the adverse effects of insecticides on the honeybee population may not be as harshly felt in Michigan as they are in states with more corn and soybean production.
And Hansen said it’s difficult to say whether insecticides play a major role in colony deaths or whether they’re just one piece of a larger problem.
“We no longer have a large population of wild honeybees in North America and that change happened in the late 1980s when varroa and tracheal mites were first introduced to North America,” Hansen said. “Those two parasitic mites have been the subject of many bee deaths.”
Roughly 28 viruses affect honeybees, he said.
Roger Sutherland of Ann Arbor, a beekeeping educator and former president of the Southeast Michigan Beekeepers Association, said that journal articles discuss all the factors causing bee deaths but don’t seem to have any answers.
And beekeepers are struggling, said Sutherland, who has been keeping bees for 45 years.
“In my first 20 years of beekeeping there were really very few problems and we had tremendous high yield and very small losses of bees in the wintertime,” Sutherland said. “And in about the mid-’80s we started getting one problem after another — parasitic mites would move in and other diseases, and we haven’t gotten rid of those problems.”
Hansen and Sutherland said the best way to protect bee populations is to use characteristics of natural selection to breed bees that are immune to new environmental threats, which would be easier then removing the factors currently killing them.
Hansen said research has been done to breed bees that are immune to mites and will actively destroy the mites.
© 2012, Capital News Service, Michigan State University School of Journalism. Nonmembers cannot reproduce CNS articles without written permission.
By PATRICK LYONS